The uses for electrical fans are numerous, including the use in areas like stone working, cement production, chemical engineering, mining, steel working, uses in public transport and disaster control, even in office buildings and simple living rooms fans can be found. The main purpose of an electrical fan is to overcome resistance in pipes while transporting air from one point to another. Fans are widely used in ventilation systems and vacuum cleaners. Upon understanding the characteristics and operations of electrical fans you can achieve great results for the ventilation system with only small efforts. Electrical fans can be separated into four categories, sorted according to their mode of air intake and output: axial fans, mixed flow fans, radial fans, and cross-flow blowers. The industry makes use mainly of three types of fans, the axial fans, the radial fans and the mixed flow fans. The most common used fans here are the mixed flow fans.
It is to be noted that the “optimized blades” described in Taiwan Patent No. 88215121 can be used for general purposes. These blades comprise:
one main fan wheel, comprising several blades, and
one air slit construction, attached to the main fan wheel, with the purpose of increasing the air transportation capability of the blades as well as increasing the general air intake.
The above mentioned construction for “optimized blades” has the capability of taking in additional air from the sides of the fan, in addition to the normal air flow. In case of a mixed flow fan the direction of the air flow has to be identical with the rotational axis of the fan wheel. Therefore, the above mentioned construction for “optimized blades”, which makes use of a air slit construction attached to the outer rim of the main fan wheel with the purpose of increasing the air intake, can not be used for mixed flow fans as long as this improvement is not adjusted to the special requirements of a mixed flow fan. This improvement is not capable of increasing the airflow through the fan and therefore not capable of increasing the function of a mixed flow fan. The construction used for reference does not meet the demands on the present invention.